Diclofenac hydroxyethylpyrrolidine which is one of diclofenac salts has lower melting point than diclofenac sodium and is a medicament suitable for a transdermal absorption preparation (Patent document 1). Also, as diclofenac hydroxyethylpyrrolidine has better water solubility than diclofenac sodium and excellent compatibility with an aqueous base material, a cataplasm containing diclofenac hydroxyethylpyrrolidine has been developed until now (Patent document 2). However, in general, the cataplasm has problems such as insufficient transdermal absorption of the drug, and low adhesiveness to the skin.                Patent document 1: Japanese Patent Publication A 63-152372        Patent document 2: Japanese Patent Publication A 6-305958        